How do I get a TN visa? And how do I become an American citizen (I'm a Canadian citizen)?

I'm a computer science student in Canada and I want to get a software engineering job in the states.

Say after I graduate I get a job in the states as an engineer.

How would I go about getting a TN Visa? And after that step, I know there's an expiry date for the TN visa? So how do I become an American citizen/permanent resident?